[analysis_server] fix nullable types in closure params of default values

Change-Id: I58d4e2770089e551f431883b385d35314eac4592
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/163001
Auto-Submit: Mike Fairhurst <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Mike Fairhurst <[email protected]>

Author: MichaelRFairhurst

pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart

@@ -800,7 +800,9 @@ class SuggestionBuilder {
     var element = parameter.enclosingElement;
     if (element is ConstructorElement) {
       if (Flutter.instance.isWidget(element.enclosingElement)) {
-        var defaultValue = getDefaultStringParameterValue(parameter);
+        // Don't bother with nullability. It won't affect default list values.
+        var defaultValue =
+            getDefaultStringParameterValue(parameter, withNullability: false);
         // TODO(devoncarew): Should we remove the check here? We would then
         // suggest values for param types like closures.
         if (defaultValue != null && defaultValue.text == '[]') {

pkg/analysis_server/lib/src/services/completion/dart/utilities.dart

@@ -15,6 +15,7 @@ import 'package:analyzer/src/dart/ast/token.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart' as protocol
     show Element, ElementKind;
+import 'package:meta/meta.dart';
 
 /// The name of the type `dynamic`;
 const DYNAMIC = 'dynamic';
@@ -169,7 +170,8 @@ protocol.Element createLocalElement(
 }
 
 /// Return a default argument value for the given [parameter].
-DefaultArgument getDefaultStringParameterValue(ParameterElement parameter) {
+DefaultArgument getDefaultStringParameterValue(ParameterElement parameter,
+    {@required bool withNullability}) {
   if (parameter != null) {
     var type = parameter.type;
     if (type is InterfaceType) {
@@ -182,7 +184,8 @@ DefaultArgument getDefaultStringParameterValue(ParameterElement parameter) {
       }
     } else if (type is FunctionType) {
       var params = type.parameters
-          .map((p) => '${getTypeString(p.type)}${p.name}')
+          .map((p) =>
+              '${getTypeString(p.type, withNullability: withNullability)}${p.name}')
           .join(', ');
       // TODO(devoncarew): Support having this method return text with newlines.
       var text = '($params) {  }';
@@ -209,11 +212,11 @@ String getRequestLineIndent(DartCompletionRequest request) {
   return content.substring(lineStartOffset, notWhitespaceOffset);
 }
 
-String getTypeString(DartType type) {
+String getTypeString(DartType type, {@required bool withNullability}) {
   if (type.isDynamic) {
     return '';
   } else {
-    return type.getDisplayString(withNullability: false) + ' ';
+    return type.getDisplayString(withNullability: withNullability) + ' ';
   }
 }
 

pkg/analysis_server/lib/src/services/correction/dart/add_missing_required_argument.dart

@@ -78,7 +78,9 @@ class AddMissingRequiredArgument extends CorrectionProducer {
           }
         }
       }
-      var defaultValue = getDefaultStringParameterValue(missingParameter);
+      var defaultValue = getDefaultStringParameterValue(missingParameter,
+          withNullability: libraryElement.isNonNullableByDefault &&
+              missingParameter.library.isNonNullableByDefault);
 
       await builder.addDartFileEdit(file, (builder) {
         builder.addInsertion(offset, (builder) {

pkg/analysis_server/test/src/services/correction/fix/add_missing_required_argument_test.dart

@@ -250,6 +250,99 @@ main() {
 ''');
   }
 
+  Future<void> test_constructor_single_closure_nnbd() async {
+    createAnalysisOptionsFile(experiments: [EnableString.non_nullable]);
+    addMetaPackage();
+    addSource('/home/test/lib/a.dart', r'''
+import 'package:meta/meta.dart';
+
+typedef int Callback(int? a);
+
+class A {
+  A({@required Callback callback}) {}
+}
+''');
+    await resolveTestUnit('''
+import 'package:test/a.dart';
+
+main() {
+  A a = new A();
+  print(a);
+}
+''');
+    await assertHasFix('''
+import 'package:test/a.dart';
+
+main() {
+  A a = new A(callback: (int? a) {  });
+  print(a);
+}
+''');
+  }
+
+  Future<void> test_constructor_single_closure_nnbd_from_legacy() async {
+    createAnalysisOptionsFile(experiments: [EnableString.non_nullable]);
+    addMetaPackage();
+    addSource('/home/test/lib/a.dart', r'''
+// @dart = 2.8
+import 'package:meta/meta.dart';
+
+typedef int Callback(int a);
+
+class A {
+  A({@required Callback callback}) {}
+}
+''');
+    await resolveTestUnit('''
+import 'package:test/a.dart';
+
+main() {
+  A a = new A();
+  print(a);
+}
+''');
+    await assertHasFix('''
+import 'package:test/a.dart';
+
+main() {
+  A a = new A(callback: (int a) {  });
+  print(a);
+}
+''');
+  }
+
+  Future<void> test_constructor_single_closure_nnbd_into_legacy() async {
+    createAnalysisOptionsFile(experiments: [EnableString.non_nullable]);
+    addMetaPackage();
+    addSource('/home/test/lib/a.dart', r'''
+import 'package:meta/meta.dart';
+
+typedef int Callback(int? a);
+
+class A {
+  A({@required Callback callback}) {}
+}
+''');
+    await resolveTestUnit('''
+// @dart = 2.8
+import 'package:test/a.dart';
+
+main() {
+  A a = new A();
+  print(a);
+}
+''');
+    await assertHasFix('''
+// @dart = 2.8
+import 'package:test/a.dart';
+
+main() {
+  A a = new A(callback: (int a) {  });
+  print(a);
+}
+''');
+  }
+
   Future<void> test_constructor_single_list() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''